Process for the purification of uranium



Jan. 20, 1959 s. ROSENFELD PROCESS FOR THE PURIFICATION OF URANVIUM 4Sheets-Sheet 1 Filed Dec. 8, 1944 INVENTOR. 5AM ROSENFELD ATTORNEY Jan.20, 1959 s. ROSENFELD 2,869,981

PROCESS FOR THE PURIFICATION OF URANIUM Filed Deb. 8, 1944 4Sheets-Sheet 2 A WASH 80L ur/0/v MAKE up WATER .s1Ev...1N 5

CQNDENSI NG 50L /0 IMPURI 7755 TO DISCARD OR SALVAGE WASH SOLUTION SOL/DE r y lMPUR/T/ES Y OXIDIZING U+++++UO2++ 25 F LTE RING u(o H) UOz WA rm1 CU CU++ H202 CuCl :u

CONDENSING T TO DISCARD 1 WATER OR SALVAGE I PREC/P/TATE a VAPOR FILTERI N c; A

TO DISCARD 0R SALVAGE i I W T EVAPORATING EVAPORATING Ag r- -fl ToFURTHER T0 FURTHER TREATMENT TREATMENT INVENTOR SAM ROSENFELD, P19. 2 BYATTORNEY PROCESS FOR THE PURIFICATION OF. URANIUM Filed Dec. 8, 1944 4Sheets-Sheet 3 DISSOLVING URANIUM METAL DEPOSITED 0N STAINLESS STEELCOLLECTOR IN (I.)HOT SOLUTION HNO 027;) 0R(2.) SOLUTION HCI 2%&H 0(o.5%) OR (3.)SOLUTION H S0 (l8%)& H 0; (10%) II cow's/V5475 AND MAKE u(l/H/VO 0f I 2/110/ 9/1 0 or I z 4 2 2 SOLUT/O/V f-l- Fe 4"!1 0,- ff-i-CONDENSING WATER n.) mvo; a, V4 (2/110/ 20/ 0 0, (3/H25048H202 iEVAPORATING I COIVOEIVTRATHJ I SOLUT/O/V U021"!- Fa ff-f H-+ /V/"""- TOFURTHER TREATMENT INVENTOR. 3 5AM ROSENFELD ATTORNEY Jan. 20, 1959 s.ROSENFELD 2,869,981

PROCESS FOR THE PURIFICATION OF URANIUM .Fil'ed Dec. 8, 1944 4Sheets-Sheet 4 MATERIAL FROM PRIOR TREATMENT SHOWN m FIGS. 2and/or 3 W 3MPRECIPITATING 0/? G03:F/?EE TA N K 07L TRATE NH40H i i T T m H3); 3)I

PRECIPITATE (N 4)2 2 19g; )4 d Fe(OH) T0 DISCARD T Fe(OH) 0R \SALVAGE lCI'(OH)3 T FLASH {IVA/20R REACTOR I BOILER CI Cl 4 N Fe Cl 3 00/4 2 00 TI y T0 CALUTRON' INVENTOR.

5AM ROSENFELQ BY ATTORNEY United States 2,36%,931 Patented Jan. 20, 1959ice PROESS FOR THE PURIFICATIGN F URANIUM Application December 8, 1944,Serial No. 567,286 Claims. (Cl. 23-145) This invention relates to thepurification of uranium and more particularly to improved reclamationprocesses that are especially adapted for use in conjunction with thesalvaging of uranium from wash solutions derived from calutrons employedin the calutron method of producing uranium enriched with U In thecopending application of Ernest 0. Lawrence, Serial No. 557,784, filedOctober 9, 1944, now Patent No. 2,709,222, there is disclosed acalutron, a machine designed to separate the constituent isotopes of anelement containing several isotopes, in order to produce the elementenriched with the selected isotope. More spestage calutron in order toproduce as a product uranium doubly enriched with U which uranium doublyenriched with U may be used commercially. in the operation of either afirst-stage calutron or a second-stage calutron the compound UCl istreated, whereby a residue of the UCL; is deposited on the parts of thecalutron disposed in the source region thereof, metallic uraniumenriched with U is deposited in the first pocket of the calutron, andmetallic uranium impoverished with respect to U is deposited in thesecond pocket of the calutron. The deposit of UCL, is recovered by awater wash step and the deposits of metallic uranium are separatelyrecovered by acid wash steps; and the three wash solutions areseparately purified, if required, to produce three separate batches of agiven compound of uranium. In this process, a first batch of the uraniumcompound mentioned, produced from the water wash derived from afirst-stage calutron, is then converted back to UCl for re-treatment inthe first-stage calutron, and a second batch of the uranium compoundmentioned, produced from the water wash derived from a second-stagecalutron, is then converted back to UCL, for re-treatment in thesecondstage calutron.

Accordingly, it is an object of the invention to provide an improvedprocess of reclaiming uranium from solutions thereof.

Another object of the invention is to provide an improved process ofsalvaging the uranium from a solution of the character mentioned thatmay be readily carried out on a commercial scale and in an economicalmanner.

Another object of the invention is to provide an .improved process ofrecovering the residue of a uranium compound which has been subjected totreatment in a calu- In accordance with tron from the parts of acalutron disposed in the source region thereof upon which the residue isdeposited.

A further object of the invention is to provide an improved process ofrecovering metallic uranium enriched with U 3 from the collector of acalutron upon which the enriched metallic uranium is deposited.

A still further object of the invention is to provide an improvedprocess of purifying uranium which has been recovered from a calutron. 7

Still another object of the invention is to provide a process ofreclaiming uranium from a wash solutionderived from a calutron in'whichthe uranium is separated from metal impurities as a chloride.

A still further object of the invention is to provide a process ofpurifying uranium contained in a wash solution derived from a calutronin which uranium is precipi tated by ammonia away from certain metalimpurities in the wash solution and separated from other metallicimpurities in said precipitate by chlorination and selectivevolatilization of said impurities.

A still further object of the invention is to provide an improvedprocess of reclaiming uranium from a wash solution derived from acalutron and converting the uranium so reclaimed into a suitablecompound for recharging a calutron.

A stillfurther object is to provide an improved process for treatinguranium compounds in a calutron in which the residual uranium compoundand impurities such as iron, copper, nickel, and chromium contained in awash solution derived from the calutron are separated from said uraniumcompound and the resulting compound is converted into a suitable chargefor further calutron treat ment.

The invention, both as to its organization and method of operation,together with further objects and advantages thereof, will best beunderstood by reference to the following specification taken inconnection with the accompanying drawings in which Figure 1 is aperspective view of a calutron in conjunction with which there may becarried out the process of the invention; Figure 2 illustrates a portionof the flow diagram of the instant process indicating the recovery ofthe residue of UCl, from the parts of the calutron disposed in thesource region thereof upon which it is deposited; Figure 3 illustratesanother portion of the flow diagram of the instant process indicatingthe recovery of the metallic uranium from the collector of the calutronupon which it is deposited; Figure 4 illustrates a further portion ofthe flow diagram of the instant process indicating the purification otthe uranium contained in the wash solutions together with the conversionthereof to a suitable calutron charging media.

Referring now more particularly to Fig. 1, there is illustrated arepresentative example of a calutron 10 of the character noted, whichcomprises magnetic field structure including upper and lower pole piecesit and 12, provided with substantially fiat parallel spaced-apart polefaces, and a tank 13 disposed between the pole faces of the pole pieces11 and 12. The pole pieces 11 and 12 carry windings, not shown, whichare adapted to be energized in order to produce a substantially uniformand relatively strong magnetic field therebetween, which magnetic fieldpasses through the tank 13 and the various parts housed therein. Thetank 13 is of tubular configuration, being substantially crescent-shapedin plan, and comprising substantially flat parallel spaced-apart top andbottom walls 14 and 15, upstandingcurved inner and outer walls 16 and17, and end walls 18 and 19. The end walls 18 and 19 close the oppositeends of the tubular tank 13 and are adapted to be removably secured inplace, whereby the tank 13 is hermetically sealed. Also,

,be evacuated to a pressure of the order of 10 to mm. Hg. Preferably,the component parts of the tank 13 are formed of steel, the bottom wallthereof resting directly upon the pole face of the lower pole piece 12,and the top wall 14 thereof being spaced'a suitable distance from thepole face of the upper pole piece 11, whereby the top and bottom walls14 and 15 constitute in elfect pole pieces with respect to the interiorof the tank 13, as explained more fully hereinafter.

j The removable end wall 18 carries an insulator 20 which supports anupstanding charge block 21, provided with a hollow central cavity 22constituting a charge receiving .pocket surrounded by rather thick sidewalls. Electrical heating elements 23 are embedded in the side walls ofthe charge block 21 and are adapted to be connected to a suitable sourceof current, whereby the charge block 21 maybe appropriately heated, thecharge turn supports an. arc block 25 formed of carbon or graphite. Theare block 25 is substantially C-shaped in plan, an upstanding slot 26being formed in the wall thereof remote from the charge block 21. Thus,the arc block 25 is of hollow construction, having a central arc cavity27 formed therein, the arc cavity 27 formed in the arc block 25communicating through the tubular member 24 with the cavity 22 formed inthe charge block 21.

Also, the removable end wall 18 carries an insulator 28, disposed abovethe insulator 20, which supports horizontally proecting cathodestructure 29, including a filamentarycathode adapted tobe connected to asuitable source of current. The cathode structure 29 projects over theupper end of the charge block 21, whereby the filamentary cathode 30overhangs and is aligned with respect to the upper end of the cavity 27formed in the are block 25. Further, an anode 31 is arranged below andin alignment with respect to the lower end of the cavity 27 formed inthe arc block 25, the anode 31 being supported by the charge block 21.The filamentary cathode 30 and the cooperating anode 31 are adapted tobe connected to. a suitable source of current.

Ion accelerating structure, including a pair of upstanding plates 32formed of carbon or graphite, is supported by respect to the slot 26formed in the wall of the arc block' 25. A suitable source of voltage isadapted to be connected between the are block 25 and the ionaccelerating structure, including the plates 32, for a purpose morefully explained hereinafter.

The removable end wall 19 carries an insulator 34 which supports anupstanding collector block 35 formed of stainless steel or the like andprovided with two laterally spa'ced-apart cavities or pockets 36 and 37which communicate with aligned slots 38 and 39 formed in the wall of thecollector block 35 disposed remote from the removable end wall 19.'Alternatively, the collector block may be fabricated of steel plate andthe inner surfaces of the pockets 36 and 37 lined with stainless steelplates. It is noted that the pockets 36 and 37 are adapted to receivetwoconstituent isotopes of an element which have been separated in thecalutron 10, as explained more fully hereinafter. Finally, the innerwall 16 carries a number of insulators 40 which support a tubular liner41 formed of copper or the like, rectangular in vertical cross-section,disposed within the tank 13 and spaced from the walls 14, 15, 16 and 17thereof. One end of the tubular liner 41 terminates adjacent theaccelerating structure,

2,sc9,9s1 t 5 M r r liner 41 terminates adjacent the collector'block 35;the tubular liner 41 constituting 'an electrostatic shield-for V thehigh-velocity ions traversing the curved paths be- L tween the slit 33formed by the plates 32 of the ion ac- V celerating structure and theslots 38 and 39 formed in I p the collector block 35, as explained morefully hereinafter. I in view of the above description, it will beunderstood that the parts of the calutron 10 carried by the removableend wall 18 constitute a source unit, and the end of the tank 13disposed adjacent the source unit constitute's the source region of thecalutron. Similarly, the parts of the calutron carried by the removableend wall '19 constitute a collector unit, and the end of the tank 13disposed adjacent the collector unit constitutes the collector region ofthe calutron. 2

Considering now the general principle of operation of' the calutron 10,a charge comprising a compound of the 1 element to be treated is placedin the charge pocket'22 in the charge block 21,-the compound of theelement mentioned being one which may be readily vaporized. 1 The cover,not shown, is then secured on the charge block 21 and the end walls 18and 19 are securely attached Y to the open ends of the tank 13, wherebythe tank 13 V is hermetically sealed. The various electrical connectionsare completed and operation of the vacuum pumping apparatus, not shown,associated with the tank 13 is 1 initiated. When a pressure of the orderof 10- to 10" mm. Hg is established within the tank 13, the electriccircuits for the windings associated with the pole pieces 11 and 12 areclosed and adjusted, whereby a predetermined magnetic field isestablished therebetween, trav- I ersing the tank 13. The electriccircuit for the heating elements 23 is closed, whereby the charge in thecharge, pocket 22 in the charge block 21 is heated and vaporized. Thevapor fills the charge pocket, 22 and is conducted S through the tubularmember 24 into thev cavity 27 formed 1 in the are block 25. The electriccircuitforthefilamentary cathode 30 is closed whereby the filamentarycathode 30 is heated and rendered electron-emissive. Then the electriccircuit between the filamentary cathode" 30 and the anode 31 is closed,whereby an arc discharge is struck therebetween, electrons proceedingfrom the fila- I mentary cathode 30'to the anode 31. The electronsproceeding from the filamentary cathode 30 .to the anode 31 break up themolecular form of the compound of the vapor to a considerable extent,producing positive. ions" of the element which is to be. enriched with aselectedone of its isotopes. V The electric circuit between the arcblockf25 and-the ion accelerating structure, including the plates 32,iscom pleted, the plates 32 being at a high negativepotential withrespect to the are block 25, wher'eby'the positive ions are attractedand accelerated to the voltage impressed between the arc block 25 andthe ion accelerating struc-f ture. More particularly, the positive ionsproceed from the interior of the cavity 27 formed in the arc block25,through the slot 26 formed in the wall thereof, and. across the spacebetween the plates 32 and the adjacent wall of the arc block 25, andthence through the slit 33 formed between the plates 32 into theinterior of the tubular liner 41. The high-velocity positive ions form a1 vertical upstanding ribbon proceeding from the cavity. 27 formed inthe arc block 25 through the slot 26 and the aligned slit 33 into thetubular liner 41.

The collector block 35, as well asthe tubular liner 41, is electricallyconnected to'the ion accelerating structure, including the plates 32,whereby there is an electric field'- free path" for the high velocitypositive ions, disposed between the plates 32 and the collector block 35within the tubular liner 41. The high-velocity positive ions en-Ifvtering the adjacent end of the liner 41 are deflected from their normalstraight-line path and form a vertical plane, passing through the slot26 and the slit 33, due to the. effect of the relatively strong magneticfield maintainedf through the space within the turn; 13 the liner llthrough which the positive ions travel, whereby the positive ionsdescribe arcs, the radii of which are proportional to the square rootsof the masses of the ions and consequently of the isotopes of theelement mentioned. Thus,

relatively light ions, a relatively light isotope of the element,describe an'interior arc of relatively short radius and are focusedthrough the slot 38 into the pocket 36 formed in the collector block 35;whereas relatively heavy ions, a relatively heavy isotope of theelement, describe an exterior arc of relatively long radius and arefocused through the slot 3? into the pocket 3? formed in the collectorblock 35. Accordingly, the relatively light ions are collected in thepocket as and are de-ionized to produce a deposit of the relativelylight isotope of the element therein, while therelatively heavy ions arecollected in the pocket 37 and are tie-ionized to produce a deposit ofthe relatively heavy isotope of the element therein.

After all of the charge in the charge pocket 22 formed in the chargeblock 21 has been vaporized, all of the electric circuits areinterrupted and the end wall 18 is removed so that another charge may beplaced in the pocket 22 and subsequently vaporized in the mannerexplained above. After a suitable number of charges have been vaporizedin order to obtain appropriate deposits of the isotope of the element inthe pockets as and 37 of the collector block 35, the end wall 19 may beremoved and the deposits of the collected isotopes in the pockets 36 and37 in the collector block 35 may be reclaimed.

Of course, it will be understood that the various dimensions of theparts of the calutron 10, the various electrical potentials appliedbetween the various electrical parts thereof, as well as the strength ofthe magnetic field between the pole pieces 11 and 12, are suitablycorrelated with respect to each other, depending upon the mass numbersof the several isotopes of the element which is to be treated therein.In this connection, reference is again made to the copending applicationof Ernest 0. Lawrence for a complete specification of a calutronespecially designed for the production of uranium enriched with theisotope U By way of illustration, it is noted that when the calutron itis employed in order to produce uranium enriched with U the compound ofuranium which is suggested as a suitable charge in the charge block 21is UCl as this compound may be readily vaporized and the molecular formof the vapor may be readily broken up to form positive ions of uraniumwith great facility. In this case, uranium enriched with U is collectedin the pocket as of the collector block 35, and uranium comprisingprincipally U is collected in the pocket 37 of the collector block 35.Also, it is noted that from a practical standpoint, the deposit ofuranium collected in the pocket 36 of the collector block 35 containsconsiderable amounts of U in view of the fact that this isotopecomprises the dominant constituent of ordinary uranium. Furthermore, thedeposit of uranium collected in the pocket 36 of the collector block 35contains a considerably increased amount of U in view of the fact thatit is not ordinarily feasible to separate U and U in the production ofrelatively large quantities of uranium enriched with U for commercialpurposes. Accordingly, in this example the uranium deposited in thepocket 36 of the collector block 35' is considerably enriched, both withU and U and considerably impoverished with respect to U as compared tonatural or normal uranium.

During the operation of the calutron it) in the production of uraniumenriched with U the compound UCll; is vaporized in the charge block 21and conducted through the tubular member 24 into the cavity 27 formed inthe arc block 25, Where it is subjected to ionization as previouslyexplained. Only a minor fraction (about of the UCI vapor is actuallyionized in the cavity 27 formed in the arc block 25 and drawn throughthe slot 216 due to d the ion accelerating structure, including theplates 32. The major fraction (about of the UCl, vapor is un-ionized inthecavity 27 formed in the arc block 25 and flows through the slot 26due to the pressure differential between the cavity 27 and the interiorof the liner 41. This major fraction of the UCL; vapor, beingun-ionized, is not at all affected by the ion accelerating structure,including the plates 32, and travels into contact with the various partsof the calutron disposed in the source region thereof, upon which partsit is condensed primarily in the compound form U01 as a residue. Moreparticularly, this residue is condensed principally upon the interior ofthe adjacent end of the liner 41, but to some extent upon the exteriorthereof, the walls of the tank 13 in the region of the source and uponthe exterior surfaces of the various elements of the source unitincluding the arc block 25, the charge block 21, etc.

More particularly, the minor fraction of the UCL; vapor is ionized toform positive atomic ions including U U++, (31+ and Cl++; and positivemolecular ions including 61 C1 UCl UCl UCl UCI UClf, UCl UCl+ and UCl++.Of these atomic and molecular ions only the singly ionized atomic ionsU+ have the required ratio between mass and charge such that they arefocused through the slots 38 and 39 into the pockets 36 and 37 formed inthe collector block 35; the atomic ions U+ of masses 234 and 235focusing through the slot 35% into the pocket 36, and the atomic ions U+of mass 238 focusing through the slot 39 into "the pocket 37, aspreviously noted.

The doubly ionized atomic ions U++ have such a ratio between mass andcharge that they are deflected along an arc of shorter radius intoengagement with the inner wall of the liner 41, where they aretie-ionized to form a deposit thereon. The singly and doubly ionizedatomic ions Cl+ and Cl++ and the singly and doubly ionized molecularions Cl and Gif have such small ratios between mass and charge that theyare deflected along arcs of very short radii into engagement with theinner wall of the liner ll adjacent the source region, where they areole-ionized to form neutral chlorine molecules, which gas issubsequently pumped from the tank 13 due the operation of the vacuumpumping apparatus previously noted. Similarly, the doubly ionizedmolecular ions UCl UCl UCl and UCl++ have intermediate ratios betweenmass and charge such that they are deflected along arcs of intermediateradii into engagement with the inner Wall of the liner ll intermediatethe source region and the collector region, Where they are de-ionized toform a deposit thereon. Finally, the singly ionized molecular ions UClUCl UCl and UCl+ have large ratios between mass and charge, such thatthey are deflected along arcs of large radii into engagement with theouter wall of the liner 41 intermediate the source region and thecollector region, where they are de-ionized to form a deposit thereon.

Accordingly, it will be understood that, after operation of the calutron10 to vaporize a reasonable number of charges of UCl in the charge block21, a considerable deposit of U01 is formed on the adjacent end of theliner 41, and that a reasonable deposit of metallic ura nium, as well asthe various uranium chlorides, is formed on the intermediate portion ofthe liner 41. These deposits represent uranium which contains thevarious isotopes U U and U in natural or normal amounts such that thesedeposits should be recovered for recycling purposes as Well as to cleanthe liner 41 and the other parts of the calutron 10 in order to insureefficient operation thereof.

Considering the present process in greater detail with reference to theproduction of uranium enriched with U it is pointed out that natural ornormal uranium comprises three isotopes, U U and U in the approximaterelative abundances 1, 1/139 and 1/ 16,700 (in numbers of atoms withreference to U respectively, or approximately 16,700, 120 and 1 atoms,respectively, in 16,821 atoms of a sample. It is highlydesirablejto-prepare large quantities of uranium enriched with thethermal-neutron fissionable isotope U for commercial purposes, and ithas been found that this end can be accomplished by employing thecalutron method. However, it is desirable that the uranium product havean enrichment factor with respect to U of the order of 400, this factorbeing defined as the quotient obtained by dividing the ratio of U to Uin the product with the ratio of U 3 to U in the original material. Nowassuming that the product is enriched by 400 in both U and U itcomprises U U andU in the approximate relative abundances 1,

AN/l3? and 409/ 16,700 (in numbers of atoms with reference to Urespectively, or'a preximately {6,76%

48,057 and 400 atoms, respectively, in 65,157 atoms of a sample. Thusthe. enriched uranium product comprises approximately 25.7% U 73.7%v Uand 0.6%

In order to obtain this desired enrichment of the uranium product 'byutilizing the calutron method, it has been found most convenient to usefirst-stage and second-stage calutrons, the first-stage calutronsemploying natural or normal uranium and producing a first-stage enrichedproduct having an enrichment factor of the order of 20 with respect tonatural or normal uranium; and the second-stage calutrons employingfirst-stage enriched uranium and producing a second-stage enrichedproduct having an enrichment factor of the order of 20 with respect tothe first-stage enriched uranium, whereby the second-stage enricheduranium product has a final enrichment factor of the order of 400 withrespect to natural or normal uranium. By employing the present process,whereby the ultimate enrichment of the final uraniumproduct is obtainedin two stages, as indicated above, each of the first-stage and thesecond-stage calutrons may be operated in the stable range and to give amaximum yield of enriched material.

Accordingly, in the present process it will be understood that intheevent the calutron comprises a firststage calutron, the deposit ofuranium in the pocket 37 in the collector block 35 has been impoverishedwith respect to the desired isotope U and is recovered there from anddiscarded;- while the deposit of uranium in the pocket 36 in thecollector block 35 has been singly enriched with respect to the desiredisotope U and is recovered therefrom and subsequently treated in asecondstage calutron. On the other hand, in the event the calutron 10-comprises a second-stage calutron, the deposit of uranium in the'pocket37 in the collector block 35 has been first enriched-and thenimpoverished with respect to the desired isotope U and is recoveredtherefrom and analyzed to determine its U content for possible"recycling'in a first-stage calutron; while the deposit of uranium in thepocket 36 in the collector block 35 has been doubly enriched withrespect to the desired isotope U and is recovered therefrom forcommercial use. 7

Thus it will be understood that in a first-stage calutron, the depositof metallic uranium in the .pocket 36 in the collector block 35 has beensubjected to one treatment and is termed singly enriched uranium, theenrichment 'being with respect to the desired isotope, U on the otherhand, in a second-stage calutron the deposit of metallic uranium in thepocket 36 in the collect-or block 35 has been subjected to twotreatments, and is termed doubly enriched uranium, the enrichment beingwith respect to the desired isotope, U

Considering now the present process in greater detail, it will beunderstood that a plant arranged to carry out the process will comprisea relatively large number of first-stage calutrons'and. a relativelysmall number of second-stage calutrons,, in addition; to. facilities forhandling, storing, recovering, purifying and converting the variousmetallic and compound forms of uranium. The starting material employedas a charge in the first-stage calutron is UCI comprising natural ornormal uranium, whereby metallic uranium singly enriched with U isdeposited in the first pocket of the collector and metallicuraniumimpoverished with respect to U is deposited in the second pocket of thecollector. Also, a large amount of UCL, is deposited as a residue uponthe parts of the first-stage calutron disposed in the sourceregionposits in the 'collcctor a'nd the UCl, residue on the liner 7 arerecovered.

More particularly, the metallic uranium various impurities includingiron, chromium and nickel are introduced in the wash solution, due tothe fact that the collector of the first-stage calutron which is thuswashed with acid is formed of the metals mentioned.

ccordingly, the wash solution containing the uraniunjt singly enrichedwith U which has been reclaimed contains considerable impurities.

in a purification process utilized in conjunction with the second-stagecalutron, in a manner more fully explained V The metallic uraniumimpoverished with hereinafter. respect to'U and deposited in the secondpocket of the collector is recovered by an acid wash process and discarded, as it contains so little U that further PIOCCSS'. ing thereof isnot feasible.

The residue of UCL; deposited on the parts of the first-stage calutrondisposed in the source region thereon principally upon the liner, isrecovered by a water wash process, whereby various impurities includingcopper, 3

iron, chromium, nickel and carbon are introduced in the. wash solution,due to the fact that the various parts of the first-stage calutron whichare thus washed with water are formed of the materials mentioned.Accord-J ingly, the wash solution containing natural or normal uraniumwhich has been reclaimed, contains considerable impurities. To this washsolution there is added makeup material in the form of a wash solutionderived from the second-stage calutron, and comprising the wash solution from the second pocket of the collector, and con taming uraniumwhich has been first enriched with U in the first-stage calutron andsubsequently impoverished with respect to U in the second-stagecalutron, as ex-.' plained more fully hereinafter.

purify said wash solution and reconvert the uranium to UC1 The UCl soproduced is then employed along with a suitable amount of makeup UCL,asa charge in the first-stage calutron.

Accordingly, the UCI, deposited in the source region 3' of thefirst-stage calutron is treated to render it recyz clable therein; thefirst-stage, enriched uranium is then stored for use in the second-stagecalutron and the first-f stage, impoverished uranium is discarded.

The starting material employed as a charge in the second-stage calutronis UCl; prepared and purified as; i hereinafter described, comprisingsingly enriched urani um whereby metallic uranium doubly enriched with Uis deposited in the first pocket of the collector and metallic uraniumwhich has been first enriched in the first-stage calutron and thenimpoverished in the second? stage calutron is deposited in the secondpocket of that,

collector. Also, a large amount of UCL; is depositedad a residue uponthe parts of the second-stage calutron dis= posed in the source regionthereof, the deposi't'bein'g primarily on the source'region end of theliner." f

singly enriched, with U and deposited in the first pocket of the col:lector is recovered by an acid wash process, whereby This wash solutionis stored and subsequently employed as makeup materal.

This composite wash i' solution is then subjected to a combinationtreatment to i several charges of UCL, comprising singly enricheduranium have been employed in the second-stage calutron, reasonabledeposits of metallic uranium have been collected in the first and secondpockets of the collector and the metallic uranium deposits in thecollector and the UCL; residue on the liner are recovered.

More particularly, the metallic uranium doubly enriched with U anddeposited in the first pocket of the collector is recovered by an acidwash process, whereby various impurities including iron, chromium andnickel are introduced in the wash solution, due to the fact that thecollector of the second-stage calutron which is thus washed with acid isformed of the metals mentioned. Accordingly, the wash solutioncontaining the uranium doubly enriched with U which has been reclaimed,contains considerable impurities. This wash solution is then purified inorder to eliminate the impurities mentioned; the impurities thuseliminated are discarded or salvaged; and the uranium thus purified isconverted into a standard compound of uranium for commercial use. Themetallic uranium first enriched with U and subsequently impoverishedwith respect to U and deposited in the second pocket of the collector isrecovered by an acid wash process, whereby various impurities includingiron, chromium and nickel are introduced in the wash solution, due tothe fact that the collector of the second-stage calutron which is thuswashed with acid is formed of the metals mentioned. Accordingly, thewash solution containing the uranium first enriched with U andsubsequently impoverished with respect to U which has been reclaimedcontains considerable impurities. The uranium in the wash solution isthen analyzed, and in the event it contains at least as much U asnatural or normal uranium, it is employed as makeup material in thepurification process utilized in conjunction with the first-stagecalutron.

The residue of UCL; deposited on the parts of the second-stage calutrondisposed in the source region thereof, principally upon the liner, isrecovered by a water wash process, whereby various impurities includingcopper, iron, chromium, nickel and carbon are introduced in the washsolution due to the fact that the various parts of the second-stagecalutron which are thus washed with water are formed of the materialsmentioned. Accordingly, the Wash solution containing the singly enricheduranium which has been reclaimed contains considerable impurities. Tothis wash solution there is added the previously stored makeup materialin the form of the Wash solution derived from the first-stage calutronand comprising the acid wash solution from the first pocked of thecollector of the first-stage calutron and containing singly enricheduranium.

This composite wash solution is then treated as will be hereinafterdescribed to eliminate the impurities mentioned and convert the uraniumback to the compound UCl This compound of UCl, is then employed as acharge in the second-stage calutron.

Accordingly, the residue of UCl, deposited in the source region of thesecond-stage calutron is treated to render it recyclable therein; thesecond-stage enriched uranium is converted to a standard compound ofuranium to be used commercially; and the second-stage impoverisheduranium is stored for use in the first-stage calutron.

Considering now the details of the recovery of the UCl, residue from theparts of either a first-stage or secondstage calutron deposited in thesource region thereof, reference is made to the portion of flow diagramillustrated in Figure 2, the parts of the calutron disposed in thesource region thereof, principally the source region end of the liner,are scrubbed and washed with hot Water whereby the residue of UCL,deposited thereon is dissolved; and various impurities including copper,iron, chromium, nickel, and carbon are introduced into the wash waterdue to the fact that the various parts of the calutron which are thuswashed with hot water are formed of the ma terials mentioned. The Washwater is then sieved in order to remove any solvent impurities which maybe picked up such, for example, as small pieces of metal and carbon.These solvent impurities may be either discarded or subjected to salvagetreatment in order to recover any occluded uranium. As shown in Fig. 2,the sieved Wash water may then be passed directly to the evaporationstage, or if desired it may first be treated with H 0 by adding a slightexcess of 10% H 0 and agitating this solution in order to oxidize thevarious contained materials.

For example, the wash water prior to the step of oxidation may containsuspended U(OH) and bits of copper and carbon; dissolved uranium in the+4 and +6 valence states, as well as dissolved copper, iron, nickel,chromium, and possibly other metals in one or more of the positivevalence states. Hence, as a result of oxidation all of the uranium isput in solution as uranyl ion, suspended copper is put in solution ascupric ion, and other dissolved materials are put in their higher stablevalence states if they are not already in such state. Carbon is notoxidized by this treatment. The effect of the oxidation on the variousmaterials contained in the wash solution may be indicated as follows:

Accordingly, the oxidized wash water contains at least the following: UOCu Pe r+++, Ni and C (carbon). The oxidized wash water is then filteredin order to remove C, which may be discarded or subjected to salvagetreatment in order to recover any occluded uranium.

in the event this filtrate is rather dilute, it may be concentrated byevaporation; otherwise this step is'omitted. In the event the filtrateis concentrated by evaporation, the water vapor which is driven off iscondensed and to it is added enough makeup water in order to provide anew wash solution, which is used again to wash the parts of the calutrondisposed in the source region thereof, in the manner previouslyexplained. This step, comprising condensing and reusing the water vaporwhich is driven oh the filtrate incident to concentration byevaporation, is advantageous in view of the fact that any uranitunentrained in the water vapor is not lost to the outside. The originalfiltrate mentioned above, or the concentrated filtrate followingevaporation, in the event this step is employed, is then stored forfurther treatment.

it will be understood that the stored water wash derived frornthe partsof the firststage calutron disposed in the source region thereof, asexplained above, comprises uranium of natural or normal composition Withreference to U while the stored Water wash derived from the parts of thesecond-stage calutron disposed in the source region thereof, asexplained above, comprises uranium which is singly enriched with UConsidering now the details of the recovery of the metallic uranium,singly enriched with U from the first pocket of the collector of thefirst-stage calutron, or of the metallic uranium, doubly enriched With Ufrom the first pocket of the collector of the second-stage calutron,reference is made to'the portion of the flow diagram illustrated in Fig.3. The inner surfaces of the first pocket of the collector of thecalutron are etched with one of a number of acid solutions, whereby thedeposit of metallic uranium, either singly or doubly enriched With U isdissolved; and various impurities in cluding iron, chromium and nickelare introduced in the acid wash solution, due to the fact that the innersurfaces of the first pocket of the collector of the calutron which arethus etchedwith the acid solution are formed of stainless steel whichcomprises the materials mentioned. Accordingly, the wash acid containsat least the followingions: UO Fe+++, Cr+++, and Ni++.

A suitable acid wash solution which may be employed for the purposementionedcomprises an aqueous solution containing HNO (approximately12%). Another suitable acid wash solution comprises an aqueous solutioncontaining l-ICl (approximately 2% and H (ap proximately 0.5%). tioncomprises an aqueous solution containing H 80 (approximately 18%) and H0 (approximately Thus, it will be understood that the first acid washsolu tion comprises'an oxidizing acid, whereas the second and third acidwash solutions comprise a separate oxidizing agent in the form of H 0Hence, the acid washsoiution employed in any case produces an oxidizingeffect upon both the uranium and the metal impurities which aredissolvedtherein.

In the event the wash acid is rather dilute inthe ions mentioned, it maye concentrated by evaporation; otherwise this step is omitted. In theevent the wash acid is concentrated by evaporation, the vapor which isdriven ofi is condensed and to itis added enough makeup HNO or HCl and H0 or H 80 and H 0 depending upon the composition of the original washacid employed, in order to provide a new wash acid which is again usedto wash the first pocket of the collector of the calutron, in the mannerpreviously explained. This step, comprising condensing the vapor whichis driven olf the wash acid incident to concentration by evaporization,is advantageous in view of the fact that any uranium entrained in thevapor is not lost to the outside. The original wash acid mentionedabove, or the concentrated wash acid following evaporation, in the eventthis step is employed, is then stored for further treatment.

It will be understood that the stored acid wash derived from the firstpocket of the collector of the first-stage calutron, as explained above,comprises uranium which is singly enriched with U while the stored acidwash derived from the first pocket of the collector of the second-stagecalutron, as explained above, comprises uranium which is doubly enrichedwith U The metallic uranium, impoverished with respect to U anddeposited in the second pocket of the collec- -tor of the first-stagecalutron, may be recovered merely by etching the inner surfaces of thesecond pocket of this collector with a suitable wash acid of thecharacter mentioned above, whereby this deposit of metallic uraniumisdissolved. This acid wash is then discarded, as it contains so littleU that further processing thereof is not feasible.

On the other hand, the metallic uranium which has been first enrichedwith respect to U and subsequently improverished with respect to U anddeposited in the second pocket of the collector of the second-stagecalutron, may be recovered by etching the inner surfaces of the secondpocket of this collector with a suitable wash acid of the charactermentioned above, whereby this deposit of metallic uranium is dissolved;and various impurities, including iron, chromium and nickel areintroduced in the acid wash solution, due to the fact that the innersurfaces of the second pocket of the collector of the calutron which arethus etched with the acid solution are formed of stainless steel whichcomprises the materials mentioned. Accordingly, the wash acid containsatleast the following ions: UO++, Fe+++, Cr+++ and Ni++. Theconsiderations concerning whether the wash acid should be concentratedare the same as those previously noted. In any case, either the originalwash acid mentioned above, or the concentrated wash acid followingevaporation, in the event this step is employed, is then analyzed inorder to determine the U content A further suitable acid wash solu- Yabout 450 C. The metallic precipitate is maintained 12 thereohln' theevent the analysisindicates that the- U content of thiswash acid is atleast as great as natural, or normal-uranium, it is stored for furthertreatment; on the other hand, in theeventthe analysis ,indicates thatthe U content of this wash acid is less-than that of natural or normaluranium, it is discarded, as further processing thereof is not feasible.1

To the stored water wash solution derived from the parts of thefirst-stage calutron disposed inthe source region thereof, there isadded the stored acid wash solu-; tion derived from the second pocket ofthe collectorof the second-stage calutron in order to produce afirst comi posite solution; this first composite solution'comprises uranium ofsubstantially natural or normal composition with reference to U Also, tothe stored water wash solution derived from the parts of thesecondrstage calutron disposed in the source region thereof, there isadded t the stored acid wash solution derived from the firstl" pocket ofthe collector of the first-stage calutron in order; to produce a secondcomposite solution; this second composite solution comprises uraniumwhich is singly en-U riched with U Finally, the stored acid washsolution; derived from the first pocket of the collector. of the sec- 7ond-stage calutron constitutes a third composite solution; this thirdcomposite solution comprises uranium which isf doubly enriched with UConsidering now the details of the purification steps of the instantprocess in which uranium is treated inam calutron and compositesolutions are produced as has been described in the foregoing, referenceis made to'the" portion of the fiow diagram illustrated in Figure 4. vThe solutions referred to which have been discussed in connection withFigures 2 and 3 comprise the follow-1 ing ionsz' UO Fe+++, Cr+++, Cu++,and Ni++. In? I accordance with the instant process, a solutioncomprisf, ing said ions is .subjected'to treatment with excess NH;, gasor carbonate-free NH OH whereby (NHQ U O Fe(OH) and- Cr(OH) areprecipitated away from most of the copper and nicket in solution in theform of ammonia complex ions, Cu(NH and Ni(NH )4i' The solution is thenfiltered and the precipitate consist ing of ammonium diuranate, ferrichydroxide, and chromic hydroxide is preferably washed with water'con-ftaining about 1% (NHQOI-I and 1% (NI-I )NO The precipitate comprisingammonium diuranate, ferric hydroxide, and chromic hydroxide is thenplaced in a chlorinating reactor which may be a closed vessel'df' Asuitable material, such as glass or other non-corrosive" material. Asuitable heating element is provided' fo r the reactor, and during thechlorinating reaction" the metallic precipitate is maintained at atemperature in the range of approximately 380 to 480 C. and preferably,

at said chlorinating temperature while carbon tet ra chloride vapor ispassed over said precipitate until substantially completechlorinationthereofis accomplishdQ Under such conditions the chromiumand iron are converted to chlorides which are volatile at the reactiontemperature mentioned and which, accordingly, will pass out of thereactor through a suitable opening. The"; chromium so chlorinated andvolatilized is in the form of CrCl and the iron as FeCl The uranium willbe a left in the reactor as the tetrachloride in which form; it i issuitable for and is utilized as calutron charging ma terial. It shouldbe noted that certain modifications may be made in the'procedure, as hasbeendescribed infithe foregoing; for example, the carbon tetrachloridemay i be carried by an inert gas such as nitrogen or carbon dioxide.Then, too, whereas I prefer to carry out the reaction at substantiallyatmospheric pressure, lower and 1 higher pressures may be resorted to asdesired. Itmay; be found convenient and desirable to reduce the prefcipitate to a granular or pulverized form prior to contacting saidprecipitate with the chlorinatingagent. a S

It will be understood that the purification of the first compositesolution in the manner desscribed above is productive of a first batchof UCl containing uranium of natural or normal composition withreference to U Also, the purification of the second composite solutionin the manner described above is productive of a second batch of UClcontaining uranium which is singly enriched with U Finally, thepurification of the third composite solution in the manner describedabove is productive of the third batch of UCL, containing uranium whichis doubly enriched with U The first and second batches of UCL, areutilized as chargin stock for first-stage and second-stage calutrons,respectively; while the third batch of UCl is available for commercialuse.

In view of the foregoing, it is apparent that there has been provided animproved process of recovering, reclaiming, purifying, and convertinguranium, both in metallic and compound form, in conjunction with thecalu tron method, whereby uranium enriched with U may be produced on alarge scale in commercial quantities.

The term uranium is employed in the present specification and claims ina generic sense, i. e., as applying to uranium whether present inelemental, ionic, or compound form, unless indicated otherwise by thecontext. Furthermore, the terms ammonia and ammonium hydroxide are usedinterchangeably, so that the use either term is to be construed ascovering the use of both substances, unless the contrary is indicated bythe context.

While there has been described what is at present considered to be thepreferred embodiment of the invention, it will be understood thatvarious modifications may be made therein and it is intended to cover inthe appended claims all such modifications as fall within the truespirit and scope of the invention.

What is claimed is:

1. In a process for reclaiming uranium values from solutions thereofwhich contain impurities including dissolved iron and copper, the stepscomprising treating said solution with ammonia to precipitate theuranium and iron from the solution in which the copper remains dissolvedas ammonia complex ions, separating said precipitate from the solution,and chlorinating said precipitate with carbon tetrachloride at atemperature in the range of approximately 380 to 480 C. to convert theuranium into uranium tetrachloride and the iron into FeCl which isvolatilized away from said uranium tetrachloride without substantialsimultaneous volatilization of said uranium tetrachloride.

2. The process of reclaiming uranium values from deposits formed uponthe parts of a calutron as a result of the processing of uraniumtetrachloride therein comprising washing said parts with an aqueoussolvent for the uranium to form a solution containing said uraniumvalues and impurities including dissolved iron, chromium, nickel andcopper, treating said solution with ammonia to precipitate the uranium,iron and chromium and leave said copper and nickel in solution asammonia complex ions, and chlorinating said precipitate with carbontetrachloride at an elevated temperature to convert said uranium intouranium tetrachloride and to volatilize and separate the iron andchromium as chlorides from said uranium tetrachloride.

3. The process of reclaiming uranium values from deposits formed on theparts of a calutron as a result of the processing of uraniumtetrachloride therein, comprising washing said parts with an aqueoussolvent for the uranium to form a solution containing said uraniumvalues and impurities including dissolved iron, chromium,

nickel and copper, treating said solution with ammonia to precipitatethe uranium, iron and chromium away from the n1ckel and copper whichremain as ammonia complexes in said solution, and chlorinating saidprecipitate with carbon tetrachloride at a temperature in the range ofapproximately 380 to 480 C, to convert the uranium into uraniumtetrachloride and to volatilize and separate the iron and chromium aschlorides from said uranium tetrachlorides.

4. The process of reclaiming uranium values from deposits formed on theparts of a calutron as a result of the processing of uraniumtetrachloride therein comprising washing said parts with an aqueoussolvent for the uranium to form a solution containing said uraniumvalues and impurities including dissolved iron, chromium, nickel andcopper, treating said solution with ammonia to precipitate the uranium,iron and chromium with the nickel and copper remaining in the solutionas ammonia complexes, and chlorinating said precipitate by contact withcarbon tetrachloride vapor in the presence of an inert gas at anelevated temperature to convert said uranium into uranium tetrachlorideandto volatilize and separate the iron and chromium as chlorides fromsaid uranium tetrachloride.

5. The process as in claim 4, wherein said inert gas is nitrogen.

6. The process as in claim 4, wherein. said inert gas is carbon dioxide.

7. The process of recovering uranium values from the residue of a watersoluble uranium compound deposited upon the parts of a calutron disposedin the source region thereof comprising washing said parts with water toform a wash solution containing said uranium values, whereby metalimpurities are introduced into said solution, treating said washsolution with ammonia to precipitate said uranium values in associationwith iron and chromium, separating said precipitate from said solution,and contacting said separated precipitate with carbon tetrachloridevapor in the presence of an inert gas under such conditions that saiduranium values are converted into uranium tetrachloride and'said ironand chromium are converted into FeCl and CrCl. respectively and arevolatilized as such from said uranium tetrachloride.

8. The process of reclaiming uranium values from the residual depositsformed on the parts of a calutron disposed in the source region thereofas a result of the processing of uranium tetrachloride thereincomprising washing said parts with water to form a solution containingsaid uranium values and impurities including the ions of iron, chromium,copper-and nickel, treating said solution with ammonia to precipitatesaid uranium values together with the iron and chromium and with thecopper and nickel remaining in solution as ammonia complex ions,separating said precipitate from said. solution, and chlorinating saidprecipitate with carbon tetrachloride at a temperature in the range ofapproximately 380 to 480 C. to convert the uranium values containedtherein into uranium tetrachloride and to volatilize and separate saidiron and chromium as chlorides from said uranium tetrachloride.

9. The process as in claim 8, wherein said chlorina-= References Citedin the file of this patent UNITED STATES PATENTS 1,070,313 Adams Aug.12, 1913 1,434,486 DAdrian Nov. 7, 1922 2,790,701 Kamen Apr. 30, 1957OTHER REFERENCES Friend: Textbook of Inorganic Chemistry, vol. 7, part3, p. 294 (1926), publ. by Charles Grifiin & Co., Ltd., London.

2. THE PROCESS OF RECLAIMING URANIUM VALUES FROM DEPOSITS FORMED UPONTHE PARTS OF A CALUTRON AS A RESULT OF THE PROCESSING OF URANIUMTETRACHLORIDE THEREIN COMPRISING WASHING SAID PARTS WITH AN AQUEOUSSOLVENT FOR THE URANIUM TO FORM A SOLUTION CONTAINING SAID URANIUMVALUES AND IMPURITIES INCLUDING DISSOLVED IRON, CHROMIUM, NICKEL ANDCOPPER, TREATING SAID SOLUTION WITH AMMONIA TO PRECIPITATE THE URANIUM,IRON AND CHROMIUM AND LEAVE